Abstract - Precision Membranes Over 38,000 people died in 2014 in the U.S. alone due to septicemia, a blood stream infection capable of eliciting the life threatening condition known as sepsis. Rapid identification and effective treatment of septicemia are essential to prevent severe sepsis and overcome the alarming mortality rates observed today. Current diagnostics require a min- imum 24-hour blood culture prior to final identification of bacteria and resistance profiles. Reducing the time to diag- nosis would offer significant benefits to patients while lowering mortality rates. Molecular identification techniques are capable of analyzing the small quantities of bacteria that would be found in an infected patient?s blood sample, but the presence of billions of blood cells prevents direct analysis. Bacteria cells must first be purified and concentrated. In this SBIR Phase I proposal, Precision Membranes seeks to evaluate the performance of surface-modified mag- netic nanoparticles as a platform for affinity-based separation of bacteria from blood with the long term goal of devel- oping an automated sample preparation tool. To evaluate the feasibility of this approach, Precision Membranes aims to selectively capture gram-positive and gram-negative bacteria in whole blood and to concentrate bacteria by efficient release from capture media into a small volume. Upon achieving 80% recovery of bacteria in less than 15 minutes, a final proof-of-concept test will be conducted to demonstrate sensitivity down to 1 CFU/mL. This research may enable the future development of a rapid sample preparation platform that could integrate with technology already rolled out to a large percentage of hospitals. This would enable healthcare providers to identify and treat a higher percentage of patients with septicemia before severe symptoms are manifest. Earlier treatment would reduce the frequency of sepsis, decrease days in hospital for infected patients, and ultimately diminish septicemia mortality rates.